If a cable is supposed to be introduced into a switch box, the wall of the box must have a hole, through which the cable is guided. Such cables often already have a plug, which can for example be molded thereon. Such plugs can be of a substantial size, for example when they are designed as a data plug for a multi-core data cable. When the cable with the plug is supposed to be guided into a hole in the wall of the box, such hole must be designed to be of a corresponding size.
In order to close off the portion of the hole left open after the cable has been guided therethrough, it is today usually covered with two plates, which are placed over the hole on the left and right of the cable, so that such plates abut. The plates have two semicircular recesses so that, when they abut, a circular opening is formed, through which the cable snugly extends.
However, because of the joint between the two plates and the circular opening for the cable, the sealing capability of this prior cover leaves much to be desired. Also the cable is not fixed, so that the plug starts being pulled out of the switch box when only a relatively light pull is exerted on the cable.
The purpose of the invention is to provide a device of the above-mentioned type guaranteeing a high sealing capability and relief against pulling the cable off of the plug.